A roadheader is an earth-boring machine which experiences high axial and radial loads on and in the frame of the machine. The roadheader includes a cutter head, a gearbox and a motor (prime mover). When the gearing, most notably the ring gear, is affixed to the housing of the gearbox, the axial and radial forces imparted on the cutter head are transmitted to the ring gear through the housing and cause misalignment of the gears and other components. The misalignment causes abnormal gear wear and ultimately destruction of the gears, carriers and other components.
Roadheaders operate in a range of motion with respect to horizontal. In other words, the cutter head of the roadheader and the gearbox affixed thereto may be inclined with respect to horizontal and creating lubrication problems with some of the bearings within the gearbox as the bearings are lifted out of the lubricating oil.
In the prior art, an internal tube requires internal connections which present the potential for leaks. These leaks allow water to enter within the gearbox and cause it to fail. The potential for leaks is increased due to the extreme vibrations that exist within the gearbox as the cutter head cuts into soil and rock. The tube vibrates within the gearbox and the connections leak due to the vibrations.
U.S. Pat. No. 7,935,020 to Jansen et al. issued May 3, 2011, states that: “A drive train for a wind turbine is provided. The wind turbine comprises a low speed shaft connected to blades of the wind turbine and a higher speed shaft connected to a generator. The drive train also includes a bearing that substantially supports the weight of at least the low speed shaft. A compound planetary gear stage is connected to the low speed shaft and the higher speed shaft, and includes a rotating carrier, a nonrotating ring gear, a plurality of planetary gears, and a rotating sun gear. The sun gear is connected to the higher speed shaft.”
U.S. Pat. No. 4,873,894 to Avery et al. issued Oct. 17, 1989, states: “A balanced free-planet drive mechanism includes a reaction ring gear, an output ring gear, an input sun gear arranged along a central axis, and a plurality of floating planet elements individually having a first planet gear engaged with the sun gear, a second planet gear engaged with the output ring gear, and a third planet gear engaged with the reaction ring gear. A required first rolling ring gear resists radially inward movement of the planet elements adjacent the third planet gear, and an optional second rolling ring gear resists radially inward movement of the planet elements adjacent the first planet gears to maintain the planetary elements essentially parallel to the central axis. A plurality of ring segments are connected to the output ring gear and engage a groove in each of the planet elements to maintain the planet elements in a preselected axial position and to transmit relatively low thrust forces. The drive mechanism is easy to assemble in a ground-engaging wheel of a truck or the like, with the output ring gear being connected to rotate with the wheel. The incorporation of the drive mechanism in a wheel eliminates the usual planet carrier and planetary bearings associated with a conventional multi-stage planetary final drive, and is lighter in weight and less costly while fitting compactly within the same general space envelope.”